Physical and numerical modelling of climate-change influenced, poorly-compacted glacial till embankments

Cutting and embankment slopes are subject to seasonally changing hydraulic boundary conditions. This results in repeated wetting and drying of the soil mass, which in certain combinations of slope geometry, soil type, fabric feared to induce significant swellshrink cycles raising serviceability issues and possibly lead to extensive down-slope displacements. Since the response of infrastructure embankments is particularly relevant in light of the current global climate change, numerical and centrifuge model studies focusing on saturated overconsolidated clay earthworks - mainly representing cutting slopes - have been carried out to investigate the above mentioned effects. Some of these tests suggested that, even a slope failure may be triggered after a number of cycles due to softening of the soil. More recent centrifuge model test results of compacted glacial till embankment with more shallow slopes reviled that the observed behaviour for heavily overconsolidated steep slopes representing cutting like conditions should not be directly adopted when investigating the behaviour of poorly compacted embankments with dominant inter-granular porosity influencing both hydraulic and mechanical response of the structure. The paper thus aims to improve the understanding by undertaking series of numerical modelling and analysis using Plaxis. The input parameters for the implemented advanced hypoplastic constitutive model that could capture the small-strain nonlinearity have been determined based on earlier and more recent advanced element test results. The boundary conditions were set to match those from the centrifuge tests, and finally the model has been refined to reproduce the experienced hydraulic and mechanical behaviour.